Adaptive range for clipping processes for video and image compression

Abstract

The various implementations described herein include methods and systems for coding video. In one aspect, a method includes receiving a video bitstream that includes encoded video data and one or more syntax elements indicating one or more clipping ranges. The method includes deriving, based on the one or more syntax elements, the one or more clipping ranges for a portion of the encoded video data. Each of the one or more clipping ranges modifies a range of sample values of the received video bitstream. The method includes performing one or more clipping operations on the encoded video data using the derived one or more clipping ranges.

What is claimed is: 
     
       1. A method of video decoding performed at a computing system having memory and one or more processors, the method comprising:
 receiving a video bitstream comprising encoded video data and one or more syntax elements indicating delta values for a dynamic clipping range for a picture of the encoded video data, wherein the delta values indicate deviations from a 10-bit range of sample values from 64 to 940; 
 deriving, based on the one or more syntax elements, the dynamic clipping range for the picture of the encoded video data, wherein the dynamic clipping range modifies the 10-bit range of sample values; and 
 performing one or more clipping operations on the encoded video data using the dynamic clipping range. 
 
     
     
       2. The method of  claim 1 , wherein deriving the dynamic clipping range comprises obtaining a modified clipping range different from a base clipping range. 
     
     
       3. The method of  claim 1 , wherein the encoded video data is encoded in accordance with a compression process, and the method further comprises:
 deriving a bit depth n of the received video bitstream based on the one or more syntax elements; 
 in accordance with a determination that the bit depth n of the received video bitstream is smaller than or equal to a bit depth m of the compression process, setting the dynamic clipping range to (0, ((1<<n)−1)<< (m−n)); and 
 in accordance with a determination that the bit depth n of the received video bitstream is larger than the bit depth m of the compression process, setting the dynamic clipping range to (0, ((1<<m)−1)). 
 
     
     
       4. The method of  claim 3 , wherein the bit depth m of the compression process comprises an extended range associated with an intermediate processing step of the compression process that is larger than an original range, the bit depth m being larger than an original bit depth of the compression process having a subset of the extended range. 
     
     
       5. The method of  claim 1 , further comprising:
 determining one or more base clipping ranges based on at least one of the received video bitstream and parameters of a compression process used to encode the encoded video data, comprising:
 in accordance with a determination that the one or more syntax elements comprises a single offset parameter for an inclusive base clipping range of the one or more base clipping ranges, wherein the base clipping range is associated with the picture of the received video bitstream, setting the dynamic clipping range based on the single offset parameter and the base clipping range; and 
 in accordance with a determination that the one or more syntax elements comprises a plurality of offset values for respective blocks:
 in accordance with a determination that the respective blocks of the received video bitstream are associated with the base clipping range of the one or more base clipping ranges, setting respective clipping ranges for the respective blocks based on the plurality of offset values and the base clipping range; and 
 in accordance with a determination that the respective blocks of the received video bitstream are associated with respective base clipping ranges of the one or more base clipping ranges, setting respective clipping ranges for the respective blocks based on the plurality of offset values and the respective base clipping range. 
 
 
 
     
     
       6. The method of  claim 1 , further comprising:
 overwriting the dynamic clipping range at a specified lower level. 
 
     
     
       7. The method of  claim 1 , wherein different clipping ranges are used for clipping operations on different color components. 
     
     
       8. A method of video encoding performed at a computing system having memory and one or more processors, the method comprising:
 receiving a video data comprising a plurality of pictures, including a first picture; 
 determining a dynamic clipping range for the first picture based on the video data, wherein the dynamic clipping range modifies a 10-bit range of sample values from 64 to 940; and 
 signaling, via a video bitstream, one or more syntax elements indicating delta values for the dynamic clipping range for the first picture. 
 
     
     
       9. The method of  claim 8 , wherein the dynamic clipping range is derived by shifting a base clipping range to obtain a modified clipping range different from the base clipping range. 
     
     
       10. The method of  claim 8 , further comprising:
 deriving a bit depth n for the video data; 
 encoding the video data in accordance with a compression process; 
 in accordance with a determination that the bit depth n is smaller than or equal to a bit depth m of the compression process, setting the dynamic clipping range to (0, (1<<n)−1)<<(m−n)); and 
 in accordance with a determination that the bit depth n is larger than the bit depth m of the compression process, setting the dynamic clipping range to (0, ((1<<m)−1)). 
 
     
     
       11. The method of  claim 8 , further comprising:
 overwriting the dynamic clipping range at a specified lower level; and 
 signaling the overwriting via the video bitstream. 
 
     
     
       12. The method of  claim 8 , wherein different clipping ranges are used for clipping operations on different color components. 
     
     
       13. A method of processing visual media data, the method comprising:
 obtaining a source video sequence that comprises a plurality of frames; and 
 performing a conversion between the source video sequence and a video bitstream of visual media data according to a format rule, 
 wherein the video bitstream comprises one or more syntax elements and a plurality of encoded pictures including a first picture, wherein the one or more syntax elements indicate delta values for a dynamic clipping range for the first picture, and wherein the delta values indicate deviations from a 10-bit range of sample values from 64 to 940; and 
 wherein the format rule specifies that:
 the dynamic clipping range for the first picture is to be derived based on the one or more syntax elements, wherein the dynamic clipping range modifies the 10-bit range of sample values; and 
 one or more clipping operations are to be performed on the first picture using the dynamic clipping range. 
 
 
     
     
       14. The method of  claim 13 , wherein the format rule further specifies that:
 a bit depth n is to be derived for the source video sequence; 
 the source video sequence is encoded in accordance with a compression process; 
 when the bit depth n is smaller than or equal to a bit depth m of the compression process, the dynamic clipping range is to be set to (0, ((1<<n)−1)<< (m−n)); and 
 when the bit depth n is larger than the bit depth m of the compression process, the dynamic clipping range is to be set to (0, ((1<<m)−1)). 
 
     
     
       15. The method of  claim 13 , wherein the dynamic clipping range is to be overwritten at a specified lower level. 
     
     
       16. The method of  claim 13 , wherein different clipping ranges are used for clipping operations on different color components.